Temporary construction scaffolds are set up at building sites to aid in effecting the construction work. Building materials such as bricks, mortar, stucco and wood have to be transported to the working floor of the scaffold. Also construction tools have to be similarly moved up to the scaffold floor. In the past this movement of materials and tools has been accomplished by hand labor using ladders propped against the scaffold side.
Scaffold mounted hoists have been described for the purpose of replacing some of this hand labor. U.S. Pat. No. 4,560,074 to Manning has a hoist comprising a winch assembly and a boom assembly. The winch assembly has a mounting bracket for attachment to the scaffold. The boom assembly mounts separately using a mast element that has a member shaped to engage and to lock on a structural element of the scaffold. The mast element also has a tube adapted to fit over the top of a scaffold column. A boom is rotatably mounted to the mast element. Pulley means are located near the junction of the mast and boom for guiding a cable through the tube. U.S. Pat. No. 3,858,728 to Fathauer has a radio control unit to send signals to a cargo spreader at the top of a cargo container crane.
Other patents of interest are U.S. Pat. Nos. 2,017,500, 2,203,113, 2,557,852, 2,670,086, 2,686,600, 3,048,371, 4,004,778, 4,191,301, 4,684,031, 4,688,688, 4,718,564, and 4,838,439; Australian Patent 163,708; French Patent 2,306,156; Japanese Patent 52-13243; and Russian Patents 827-369, 840-006, and 1390-177.